Pierre Rigo

Right ventricular dysfunction detected by gated scintiphotography in patients with acute inferior myocardial infarction.

Twenty-seven patients with acute myocardial infarction not complicated by cardiogenic shock and ten normal volunteers were studied with gated cardiac blood pool scans. The ratio of right ventricular area/left ventricular area (RVA/LVA) determined from the left anterior oblique end-diastolic scans was examined. The ratio was 1.11 ± .06 in the normal volunteers. In patients with anterior infarction the ratio fell to 0.75 ± .12 (P < .05) due to left ventricular enlargement. In those with inferior infarction the ratio was 1.12 ± .23 which was greater than in those with anterior infarction (P < .05) due to enlargement of both the left and right ventricles. Six patients with cardiogenic shock, three with inferior and three with anterior infarction were studied. The three with anterior infarction had left ventricular enlargement and a decrease in the ratio of RVA/LVA to 0.62 while the three with inferior infarction had an increase in the ratio to 2.05 suggesting right ventricular dilatation and dysfunction. These studies suggest a high incidence of right ventricular dysfunction in patients with inferior myocardial infarction.

Value and limitations of segmental analysis of stress thallium myocardial imaging for localization of coronary artery disease.

This study was done to determine the value of thallium-201 myocardial scintigraphic imaging (MSI) for identifying disease in the individual coronary arteries. Segmental analysis of rest and stress MSI was performed in 133 patients with arteriographically proved coronary artery disease (CAD). Certain scintigraphic segments were highly specific (97-100%) for the three major coronary arteries: anterior wall and septum for the left anterior descending (LAD) coronary artery; the inferior wall for the right coronary artery (RCA); and the proximal lateral wall for the circumflex (LCX) artery. Perfusion defects located in the anterolateral wall in the anterior view were highly specific for proximal disease in the LAD involving the major diagonal branches, but this was not true for “septal” defects. The apical segments were not specific for any of the three major vessels. Although MSI was abnormal in 89% of these patients with CAD, it was less sensitive for identifying individual vessel disease: 63% for LAD, 50% for RCA and 21% for LCX disease (narrowings > 50%). Sensitivity increased with the severity of stenosis, but even for 100% occlusions was only 87% for LAD, 58% for RCA and 38% for LCX. Sensitivity diminished as the number of vessels involved increased: with single-vessel disease, 80% of LAD, 54% of RCA and 33% of LCX lesions were detected, but in patients with triple-vessel disease, only 50% of LAD, 50% of RCA and 16% of LCX lesions were identified. Thus, although segmental analysis of MSI can identify disease in the individual coronary arteries with high specificity, only moderate sensitivity is achieved, reflecting the tendency of MSI to identify only the most severely ischemic area among several that may be present in a heart. Perfusion scintigrams display relative distributions rather than absolute values for myocardial blood flow.

Left ventricular function in acute myocardial infarction evaluated by gated scintiphotography

Ten normal volunteers and 38 patients with acute myocardial infarction were evaluated by biplane gated blood pool scanning. The mean left ventricular end-diastolic volume in those with infarction was 125 ± 41 ml/m2 compared to 82 ± 10 ml/m2 in the normals. The left ventricular end-systolic volume was 82 ± 35 ml/m2 compared to 35 ± 4 ml/m2, and the left ventricular ejection fraction 36 ± 8% compared to 56 ± 3% in the normals. Thirty-six of the 38 patients with infarction had an area of akinesis which ranged from 15 to 59% of the left ventricular wall. Patients with acute myocardial infarction were found to have a significant increase in left ventricular end-systolic volume and decrease in ejection fraction compared to normals. The end-diastolic volume was, however, increased only in those with an elevated left ventricular filling pressure or decreased cardiac index.Follow-up studies obtained in 20 patients between one week and three months following infarction showed that in the 14 who improved clinically, left ventricular ejection fraction significantly increased from 38 to 45% (P < 0.001) while in six who failed to show clinical improvement or worsened, left ventricular ejection fraction remained at 30%.Left ventricular ejection fraction was significantly greater and the extent of akinesis significantly less in the patients who survived compared to those who died.

Measurement of aortic and mitral regurgitation by gated cardiac blood pool scans.

A simple, noninvasive radionuclide technique which measures the severity of valvular regurgitation has been developed. The technique compares right and left ventricular stroke volume indices (change in counts between diastole and systole over the left and right ventricles) from 450 LAO gated cardiac blood pool scans. In 14 control subjects, the left-to-right ventricular stroke index ratio was near unity (1.15 ± 0.15 [SD]). In 26 patients with mitral and/or aortic regurgitation it was larger (range 1.36-5.30, mean 2.44). Comparison between the stroke index ratio and qualitative angiographic estimates of regurgitation revealed good agreement (F = 45.5, p < 0.001). Gated cardiac blood pool scans permit noninvasive assessment of the severity of valvular regurgitation.

Hemodynamic and prognostic findings in patients with transmural and nontransmural infarction.

One hundred and eleven patients with transmural (TMI) and 49 with nontransmural myocardial infarction (NTMI) underwent hemodynamic investigation within 24 hours of onset of symptoms. Patients with NTMI were subdivided into those with ST-segment or T-wave changes alone with a normal QRS complex (NTMI-A) and a group with QRS abnormalities that did not satisfy the criteria for TMI (NTMI-B). Those with TMI had a significantly higher peak creatine phosphokinase (CPK) than those with NTMI: 840 plus or minus 99 and 336 plus or minus 69, respectively, P smaller than 0.05. There was not difference in peak CPK between those with NTMI-A and B. The incidence of arrhythmias and cardiac failure, and routine hemodynamic findings except for left ventricular filling pressure were similar in those with TMI and NTMI. There was not significant difference in in-hospital mortality between those with TMI (22%) and NTMI (33%). There was however a significant difference in in-hospital mortality between those with NTMI-A (0%) and NTMI-B (27%, P smaller than 0.05). The late mortality in those surviving their initial hospitalization was also not different between those with TMI (18%) and NTMI (19%) during a mean follow-up period of 20.2 months. In contrast to the in-hospital mortality those with NTMI-A had a late mortality similar to those with NTMI-B and those with TMI.

Ventricular arrhythmias in the late hospital phase of acute myocardial infarction. Relation to left ventricular function detected by gated cardiac blood pool scanning.

Abnormalities of left ventricular function and extent of myocardial infarction were studied in relation to prevalence of late ventricular premature contractions (VPCs) in 36 patients in the convalescent stage of acute myocardial infarction (MI). Left ventricular ejection fraction (EF) and percent akinesis (%A) were calculated from gated cardiac blood pool scans; myocardial infarct size was estimated from peak CPK values; and VPCs were detected by 24 hour ambulatory ECGs 2-4 weeks following hospitalization for acute MI. Twenty-two patients had either zero (class 0) or < 30/hour unifocal VPCs (class I). Fourteen patients had > 30/hour unifocal (class II), multifocal (class III) or coupled VPCs (class IV), including ventricular tachycardia. Thirteen of 14 class II-IV patients had EF < 40% compared with only 8 of 22 class 0-I patients. Class II-IV patients had significantly lower mean EF (30.5 ± 2.3 se to 49.6 ± 4.0) P < 0.01, higher mean %A (28.1 ± 2.2 to 16.9 ± 3.7) P < 0.05, and higher mean peak CPK (1350 ± 187 to 721 ± 155) P < 0.05 than class 0-I patients. These data suggest that VPCs may not be an independent risk factor for sudden cardiac death in the convalescent phase of MI.

Influence of coronary collateral vessels on the results of thallium-201 myocardial stress imaging

Abstract Although collateral vessels are commonly seen in patients with coronary disease, their functional significance has been debated. In this study segmental analysis of thallium-201 perfusion scintigrams obtained at rest and after exercise was made in 124 patients with angiographically proved coronary artery disease to determine whether collateral vessels could provide protection front myocardial ischemia during stress. All 15 coronary arteries that were completely occluded and had no collateral vessels showed a corresponding stress perfusion abnormality, but only 65 of 92 occluded arteries with angiographically visualized collateral vessels showed a corresponding stress defect (P

Scintiphotographic Evaluation of Patients with Suspected Left Ventricular Aneurysm

Twenty-two patients with a history of myocardial infarction and suspected of having a left ventricular aneurysm were evaluated by routine clinical studies, gated cardiac blood pool scanning, and contrast left ventriculography.Thirteen patients were found to have a localized left ventricular aneurysm and nine demonstrated diffuse left ventricular hypokinesis on contrast angiography. The patients with localized left ventricular aneurysms could not be separated from those with diffuse left ventricular hypokinesis on the basis of the routine clinical evaluation including the chest roentgenogram or the finding of ST-segment elevation in the electrocardiogram. Scintiphotographic studies identified the nine with diffuse hypokinesis and twelve of the thirteen with a localized left ventricular aneurysm. In one patient with a calcified left ventricular aneurysm filled with clot, the cardiac blood pool scan showed an area of akinesis which corresponded to that seen on contrast angiography, but the aneurysm could not be detected.In nineteen of the patients in whom adequate measurements were obtained, left ventricular end-diastolic volume and ejection fraction by both contrast angiography and gated cardiac blood pool scintiphotography demonstrated a good correlation, r = 0.92 and 0.87, respectively. There was also a good correlation between the extent of left ventricular akinesis seen on contrast angiography and gated scintiphotography, r = 0.97.This study demonstrates that biplane gated cardiac blood pool scans are useful in differentiating patients with localized left ventricular aneurysms from those with diffuse left ventricular hypokinesis.

Stress thallium-201 myocardial scintigraphy for the detection of individual coronary arterial lesions in patients with and without previous myocardial infarction☆

The value of stress thallium-201 scintigraphy for detecting individual coronary arterial stenoses was analyzed in 141 patients with angiographically proved coronary artery disease, 101 with and 40 without a previous myocardial infarction. In patients without infarction, the sensitivity for detecting greater than 50 percent narrowing in the left anterior descending, the right and the left circumflex coronary artery was 66, 53 and 24 percent, respectively. In those with a previous infarction, the sensitivity for demonstrating disease in the artery corresponding to the site of infarction was 100 percent for the left anterior descending, 79 percent for the right and 63 percent for the left circumflex coronary artery. In patients with a prior anterior infarction, concomitant right or left circumflex coronary arterial lesions were detected in only 1 of 12 cases, whereas in those with previous inferior or inferolateral infarction, the sensitivity for left anterior descending coronary artery disease was 69 percent. Because of the reasonably high sensitivity for detecting left anterior descending arterial disease, irrespective of the presence and location of previous infarction, myocardial scintigraphy was useful in identifying multivessel disease in patients with a previous inferior infarction. However, because of its relative insensitivity for right or left circumflex coronary artery disease, scintigraphy proved to be a poor predictor of multivessel disease in patients with a prior anterior infarction and in patients without previous myocardial infarction.

Gallium-67 myocardial imaging for the detection of bacterial endocarditis.

Eleven patients with a clinical diagnosis of bacterial endocarditis underwent scintillation scanning of the precordial region 2-7 days after the intravenous administration of 3 mCi of gallium-67 citrate. Seven had positive scans, 3 of which were confirmed by postmortem imaging at autopsy. Serial images revealed the scans to be frequently negative at 48 hours and positive from 3 to 8 days following injection. Uptake was not seen in the region of the myocardium 48 hours or longer after the injection of 15 patients without endocarditis used as controls.